Sleep Mystery is an engaging, authentic, interactive STEM classroom game for a non-STEM audience. This serious STEM game was designed to address three important issues: the role of healthy sleep habits on long-term chronic disease the connection between poor sleep hygiene and prescription drug abuse the declining interest of U.S. students as they reach middle school in STEM and health sciences Through participation in hands-on, intense, real-world case scenarios, students will understand the role they personally play in forming their own health habits that impact chronic and acute disease. Designed for health, life science, or physical education teachers, this game exercises Next Generation Science Standard practices as students work to solve a real medical mystery: the unexplained death of a 50-year-old man who was being treated by his physician for an inability to sleep. A paper prototype that used 4 instructor-led learning stations was piloted in 8 sessions with 285 students from grades 4-8, and again with 24 science teachers. The response was overwhelmingly positive: 64% students reported their interest in science professions improved, and 60% that their confidence in science improved. Teachers requested a version that they could use in their classrooms to reach more middle-school students. Based on this successful classroom pilot, we propose to develop and evaluate a web-based, playable prototype for middle-school students taking required health, physical education, or life science classes. Our specific aims are: Aim 1: Prototype digital game development. Working with middle school health and science teachers, we will confirm the learning outcomes, content, and approach are appropriate for our audience and meet specific health and science standards. Along with the playable prototype, we will develop supporting lesson plans for teachers. Each chapter will use data from the actual case, and allow students to play the role of different STEM professionals, while obtaining clues and detecting potential causes of patient?s demise. Aim 2. Evaluation of the digital game prototype for engagement, learning gains in health content, and increased interest in STEM and health sciences careers. Evaluation will collect data through pre- and post-game surveys of students, game-play analytics, and structured interviews of teachers. Instruments will contain both researcher- generated (engagement, health content) and previously validated measures (interest in STEM careers). Populations will include no less than 120 students from two schools, one with significant underrepresented minorities: 60% Latino and 30% African American students. The evaluation will follow a quasi-experimental design, selecting a subset of students to participate in human-facilitated game as a control. The final target in Phase I will be results for the web-based game that are equal or better to the instructor-led classroom pilot for these same measures.